1. Field of the Invention
The present invention relates to a driving head, and more particularly to a driving head-changeable tool.
2. Description of the Prior Art
In prior art of two-part form of connecting head, a polygonal ball-shaped head of a support rod is received in a receiving slot of a working head. And the receiving slot corresponds to the polygonal ball-shaped head in shape. The support rod is assembled and fixed with the working head through a connecting structure. The support rod is pulled out and rotates relatively to the working head. This kind of connecting head is disclosed in TW566284 and TWM357344.
A structure as described in the TW566284, having an inner wall of the receiving slot formed as polygonal-shaped and contacting with the polygonal ball-shaped head through surfaces. When the support rod is driven to rotate relatively to the working head by an electrical driving device with a high speed, the receiving slot and the polygonal ball-shaped head are easily blocked because of friction between each other. Also, the electrical device and the two-part form of connecting head are damaged. Furthermore, the friction also causes energy loss and makes work efficiency worse.
A structure as described in the TWM357344, having a lateral wall of the receiving slot formed with protruding flanges corresponding to the polygonal ball-shaped head. The protruding flanges are equal spaced-apart and longitudinally disposed on the lateral wall. A number of the protruding flanges corresponds to the polygonal ball-shaped head. Each of the protruding flanges includes a camber surface for contacting with the polygonal ball-shaped head. The support rod and the working head are linking-up in rotation and it improves the disadvantages in the TW566284.
However, either TW566284 or TWM357344 has a structure which is unformed with blocking flanges to block corner portions of the polygonal ball-shaped head. The driving head easily prolapses, and it stops the work, reduces work efficiency and causes secure problems.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.